WiMAX, described in the IEEE 802.16 Wireless Metropolitan Area Network (MAN) standard (IEEE 802.16-2005), allows for high-speed wireless data transmissions over long distances. The core components of an 802.16 network are base stations (BS) and subscriber stations (SS). An SS may be a mobile station (MS). The WiMAX network was originally designed as a Point-to-Multipoint (PMP) architecture. The 802.16-2005 standard defines a connection-oriented mechanism for data flow between BS and MS. A Connection ID (CID) is defined to associate a data flow service with a connection. CIDs are also used by MS's in PMP networks to tell which data bursts in a DL frame should be decoded and which should not.
WiMAX is now progressing to large scales and full mobility. In order to extend access coverage, optimize utilization of radio resources, and support flexible mobility, WiMAX is migrating from the one-hop PMP architecture to a multi-tier PMP topology, referred to as MMR (Mobile Multi-hop Relay). MMR is a tree-like relay architecture wherein a BS and SS may be separated by one or more relay stations (RS).
The MMR architecture presents new complications. MMR is different from legacy one-hop PMP access, where radio resources are allocated by centralized control in the Base Station (BS). The multi-tier MMR may require a distributed radio source allocation schema across BS and RS, or a hybrid schema of both centralized and distributed control. This distributed or hybrid schema should provide a relay operation to forward the data frame Down Link (DL) and Up Link (UL) between a BS and MS's via the RS's. Further, mobility functionality must be provided for MS's and RS's, both inter-tree and intra-tree.
Use of CIDs in MMR networks becomes a critical issue. Current suggested relay solutions require all RS to acquire, store, and decode the MAC PDUs in DL frames to get the CIDs of the MS for relay operation. As a result, RS MAC PDU decoding consumes excessive resources and RS forwarding tables become very large and ultimately unmanageable. Furthermore, to execute a handover of an MS from one branch to another branch of the MMR network, all the MS CIDs have to be transferred from all RS along the old branch to all RS along the new branch, resulting in very inefficient MMR relay operation. New relay and mobility solutions are required for 802.16 MMR networks in order to provide commercially reasonable efficiency and performance.